Bump webdriver from 3.0.2 to 3.0.3 in /lib/web_ui (#46400)

Bumps [webdriver](https://github.com/google/webdriver.dart) from 3.0.2 to 3.0.3.
<details>
<summary>Changelog</summary>
<p><em>Sourced from <a href="https://github.com/google/webdriver.dart/blob/master/CHANGELOG.md">webdriver's changelog</a>.</em></p>
<blockquote>
<h2>3.0.3</h2>
<ul>
<li>Include a content-type header when sending requests from <code>async_html.dart</code>.
The content-type is necessary for compatibility with GeckoDriver 0.27.0 and
newer versions.  The content-type header was already being sent in IO clients
for a long time, so only the HTML client had to be updated.</li>
</ul>
</blockquote>
</details>
<details>
<summary>Commits</summary>
<ul>
<li>See full diff in <a href="https://github.com/google/webdriver.dart/commits">compare view</a></li>
</ul>
</details>
<br />

[![Dependabot compatibility score](https://dependabot-badges.githubapp.com/badges/compatibility_score?dependency-name=webdriver&package-manager=pub&previous-version=3.0.2&new-version=3.0.3)](https://docs.github.com/en/github/managing-security-vulnerabilities/about-dependabot-security-updates#about-compatibility-scores)

Dependabot will resolve any conflicts with this PR as long as you don't alter it yourself. You can also trigger a rebase manually by commenting `@dependabot rebase`.

---

<details>
<summary>Dependabot commands and options</summary>
<br />

You can trigger Dependabot actions by commenting on this PR:
- `@dependabot rebase` will rebase this PR
- `@dependabot recreate` will recreate this PR, overwriting any edits that have been made to it
- `@dependabot merge` will merge this PR after your CI passes on it
- `@dependabot squash and merge` will squash and merge this PR after your CI passes on it
- `@dependabot cancel merge` will cancel a previously requested merge and block automerging
- `@dependabot reopen` will reopen this PR if it is closed
- `@dependabot close` will close this PR and stop Dependabot recreating it. You can achieve the same result by closing it manually
- `@dependabot show <dependency name> ignore conditions` will show all of the ignore conditions of the specified dependency
- `@dependabot ignore this major version` will close this PR and stop Dependabot creating any more for this major version (unless you reopen the PR or upgrade to it yourself)
- `@dependabot ignore this minor version` will close this PR and stop Dependabot creating any more for this minor version (unless you reopen the PR or upgrade to it yourself)
- `@dependabot ignore this dependency` will close this PR and stop Dependabot creating any more for this dependency (unless you reopen the PR or upgrade to it yourself)

</details>

Author: dependabot[bot]

lib/web_ui/pubspec.yaml

@@ -45,7 +45,7 @@ dev_dependencies:
   uuid: 4.1.0
   watcher: 1.1.0
   web_socket_channel: any
-  webdriver: 3.0.2
+  webdriver: 3.0.3
   webkit_inspection_protocol: any
   yaml: 3.0.0
   web_test_utils: